Synthesis and characterization of bimodal mesoporous silica

Abstract

Mesoporous silica with controllable bimodal pore size distribution was synthesized with cetyltrimethylammonium bromide (CTAB) as chemical template for small mesopores and silica gel as physical template for large mesopores. The structure of synthesized samples were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N₂ adsorption-desorption measurements. The experimental results show that bimodal mesoporous silica consists of small mesopores of about 3 nm and large mesopores of about 45 nm. The small mesopores which were formed on the external surface and pore walls of the silica gel had similar characters with those of MCM-41, while large mesopores were inherited from parent silica gel material. The pore size distribution of the synthesized silica can be adjusted by changing the relative content of TEOS and silica gel or the feeding sequence of silica gel and NH₄OH.

Keywords

bimodal pore size distribution / mesoporous silica / synthesis / characterization

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